University of Bristol

Siyuan Yu

Mark G Thompson

Ian White

Richard Vincent Penty

Xinlun Cai

The invention relates to methods, devices, systems and uses of such systems for the generation and detection of electromagnetic fields carrying orbital angular momentum. An electromagnetic wave placed in a resonator having a closed-loop waveguide supporting a guided wave propagating at resonance with angular order, p, and with an angular grating patterned in the closed-loop waveguide, the angular grating having a integer number, q, of grating elements. The angular grating selectively couples the guided wave mode to a free space radiation mode having an OAM quantity, l, and out-of-plane wave vector component, krad,z, and wherein significant coupling to the grating occurs only when the following wave matching condition is satisfied: l=p&#x2212;mq where: m is the diffraction order of the angular grating, m=1, 2, 3, . . . ,.

Orbital angular momentum

A tunable lasing device () comprising a ring-shaped laser cavity (), an optical gain element (), a bi-directional output coupler () and a frequency selection means (). The frequency selection means is generally a grating with a refractive index that determines a grating reflection frequency. Single mode laser operation is achieved where a cavity mode frequency of the ring-shaped laser cavity coincides with a grating reflection frequency. The refractive index of the grating can be modified by the injection of a variable current. In this way, the lasing frequency can be rapidly tuned between cavity mode frequencies.

Tunable ring laser with external grating operation in a single mode

An optical crosspoint switch structure is disclosed. The switch permits light signal to be diverted from any arbitrary number of input ports to any or several of an arbitrary number of output ports. The switch consists of two groups or intercepting optical waveguides formed on a planar substrate, which are the input and output waveguides respectvely. At each intersection another waveguide is formed above the input and output waveguides. Optical coupling between this upper waveguide and the input/output waveguides is controlled by an electrical or optical signal. The upper waveguide has a corner mirror at the intersection. When the control signal allows, light couples from the input waveguide to the upper waveguide. After being reflected by the corner mirror, the light couples from the upper waveguide into the output waveguide. The upper waveguide incorporates the active switching element. Allowing high modulation depth and low crosstalk level.

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Bristol, United Kingdom

Siyuan Yu